8 MASS. EXPERIMENT STATION BULLETIN 436 



before plowing and were poorest on plots on which corn was allowed to stand 

 over winter before plowing. Where nitrogen had been added before plowing, 

 there was considerable increase both in yield and in quality; but the deleterious 

 effects of corn on tobacco may not be entirely alleviated by the use of nitrogen. 



The yields of tobacco on the ammonium sulfate plots were greater than on 

 the nitrate plots, but the quality of the tobacco was inferior. 



The Absorption of Chemical Elements by Food Plants. (Walter S. Eisen- 

 menger and Karol J. Kucinski.) The experiment was set up to compare the 

 intake of elements when used singly and in pairs. The intake of calcium and 

 magnesium was studied as well as the influence of the copper ion on the intake of 

 magnesium and the movement of magnesium in the plant. 



Magnesium added to the soil caused an increase of magnesium in the plants 

 in all instances. When calcium was added to the soil, most of the plants studied 

 contained more calcium but approximately a fourth showed no increase. 



In water solutions copper ions lowered the transfer of magnesium. In the field 

 this was not observed, probably because of the small amount of copper added 

 (75 p. p.m.) and the buffer action of the soil. The change in the composition of 

 seeds from plants under varied conditions of ion application was insignificant. 



There seemed to be a tendency for the calcium content of plant tissue to be 

 increased when copper was added to the soil. No explanation can be made of 

 this unusual behavior. 



The magnesium content and, to a lesser degree, the calcium content of foods 

 and feeds can be increased by application of the salts of these elements to the 

 soil. In the seedling stage, the transfer of magnesium from the seed and the 

 water medium to the aerial portion of the plant was diminished by as small an 

 amount of copper as one-half part per million. 



Magnesium Requirements of Certain Plants. (Walter S. Eisenmenger and 

 Karol J. Kucinski.) Work on this project included study of the relationship of 

 seed plant development and the need of plants for magnesium, as well as the re- 

 lation between intake of magnesium and the supply of the element in the soil. 

 This part of the project was designed to ascertain whether plants which readily 

 show signs of magnesium deficiency take up more or less magnesium when an 

 ample supply is present in the soil than plants which do not show symptoms 

 readily. 



Plants vary greatly in their reaction to soils of low magnesium content, and 

 plants of a lower order of development show the deficiency more quickly than 

 plants of extremely high development. Thus the buttercup (Ranunculus), the 

 mallows, geraniums, elms, anemones, buckwheat, rhubarb, cabbage, and tobacco 

 always react to low magnesium soils; while plants like the asters, dandelions, 

 sunflowers, ragweed, lamb's-quarters (Chenopodium album), pigweed {Amaranthus 

 retroflexus), and the grasses do not show any symptoms of magnesium deficiency 

 when grown on the "deficiency" plots. There are two conditions where the 

 above does not hold. First, when plants have been changed by selection or plant 

 breeding, there is no certainty that these species will react at all to soils of low 

 magnesium content. Second, and less frequently, certain plants such as the 

 portulaca and blackberry, for example, when grown in low magnesium soil show 

 deficiency only in subnormal growth and not through chlorosis. Some plants, 

 as the mallows and buttercups, normally take up comparatively little rriagnesium, 

 and their magnesium content, compared with that of other plants, is low. There 

 is evidence that such plants react more quickly to low mag nesium soils. 



The ability to recognize the plants which are not tolerant to low magnesium 

 content of the soil would afford a chance to correct this condition when the need 



